Epithelium Flashcards
How to make an epithelium?
-Thin, semi permeable
-Connections between cells
-sheet anchored to something
-regenerative ability
-polarity (apex and base)
-apical specializations (absorption and movement of particles)
-Durability to the environment
Tight junctions
-Cytoskeletal component: actin filaments
- Seling of adjacent cells to one another
-movement of particles
-separation of apical and basolateral components of membrane
Adherent junctions
-Cytoskeletal component: actin filament
-Link the cytoskeleton of cells
strengthens and stabilizes tight junctions
Desosome
-Cytoskeletal component: intermediate filament (keratin)
-strengthens tissue between cells
Hemidesosome
-Cytoskeletal component: intermediate filament
-Anchor cytoskeleton to basal lamina
Gap Junctions
-NO cytoskeletal component
-Transfer of small molecules and ions between cells
Enemies of tight junctions
-Clostridium perfrigens: Food poisoning
-Helicobacter pylori: Gastric ulcers
Apical specializations
-Microvilli
-Cilia
-Sterocilia
Microvilli
-Absorption epithelia has microvilli on the surface
-Microvilli appears as a brushed border in small intestines
-Increases absorption by increasing surface area
Celiac disease
-Gluten sensitivity due to loss of microvilli in the small intestine
-an immune reaction to wheat gluten, which leads to inflammation of the intestines.
-Changes structure of epithelia leading to malabsorption.
Stereocilia
-moves cells and fluids along tubes, and they sense movement
-Found in epididymis of males and inner ear sensory cell
Cilia
-Long and highly motile: microtubules not microfilaments
-Abundant in columnar and cuboidal cells
- 9 +2 assembly called axonemes
Types of covering (lining) of epithelium
-Simple: squamous, cuboidal, and columnar
-Stratified: Squamous keratinized, squamous non-keratinized, cuboidal, columnar, and transitional
Simple squamous
- Lining of vesicles and cavities
-Facilitate movement of viscera
-Active transport by pinocytosis
-Secretion of biologically active molecules
Simple Cuboidal
-Lining of thyroid and ovaries
-Covering and secretion
Simple Columnar
-Lining of intestines and gall bladder
-Protection, lubrication, absorption, and secretion
Stratified Squamous Keratinized (dry)
-Epidermis
-Protection and prevention of water loss
Stratified Squamous Non-keratinized (moist)
-mouth, esophagus, vagina, larynx, anal canal
-Protection, prevention of water loss, and secretion
Stratified Cuboidal
-Sweat glands, developing ovarian filaments
-protection and secretion
Stratified Transitional
-Bladder, uterus, renal calyces
-Protection and distensibility
Stratified columnar
-Conjuctiva
-Protection
Psedustratified
-Layers of cells w/ nuclei at different levels. Not all cells reach the surface, but all cells are anchored to the basal lamina
-Lining of trachea, bronchi, and nasal cavity
-Protection, secretion, and cilia-mediated transport of particles trapped in mucus
Simple secretory cells
-Goblet cells: unicellular glands that are scattered secretory cells
Exocrine simple glands
-Simple tubular
-Branched tubular
-Acinar
Branched Acinar
-Coiled tubular
Simple tubular
-Mucuous glands of the colon and intestinal glands
-Elongated secretory portion, short or absent duct
Branched tubular
-Glands in the uterus and stomach
-Several long secretory parts that join one duct
Simple coiled tubular
-Sweat glands
The secretory portion is long and coiled
Simple acinar
-Small mucous glands along the urethra
-Rounded sac-like secretory portion
Simple branched acinar
-sebaceous glands of the skin
-Multiple sac-like secretory portion
Exocrine compound glands
-Tubular
-Acinar
-Tubuloacinar
Compound Tubular
-Elongated coiled secretory portions and ducts that lead to larger ducts
-Submucous gland in the duodenum
Compound acinar
-Several sac-like secretory units
-Exocrine pancreas
Compound Tubuloacinar
-Salivary glands
-Ducts of tubular and acinar
Secretory Epithelia and Glands
-Merocrine
-Halocrine
-Apocrine
Merocrine Gland
-Vesicles release contents by exocytosis
-mucous or serous
-well-developed RER and Golgi complex
Serous cells of merocrine glands
- Synthesize proteins such as digestive enzyme
-Pancreas and parotid salivary glands
Mucous cells of merocrine glands
-Produce mucins, which are glycoproteins
-Mucins become hydrated and then become mucus
Holocrine glands
-Cells disintegrate
-Involved in acne: excess secretion of sebum and testosterone in both genders leads to blocked ducts. Commensal bacterium in ducts leads to inflammation
Apocrine glands
- Tips of cells with secretion pinch-off
-Mammary gland
Renewal and repair of Epithelium
-Epithelia are capable of rapid repair and replacement of apoptotic and damaged cells
-Liver: when damaged or removed healthy liver cells begin proliferation to regenerate their tissue to normal function
Abnormal renewal of epithelium
-Carcinoma: proliferation of cells no longer under normal control. Both benign and malign tumors
Adenocarcinomas
-Malign tumors derived from mucus membranes
-Affects glands that secrete such as breast, lungs, colo, prostate, and bladder
Squamous cell carcinomas
-Flat cells on surface of the skin
-Lining of hollow organs and respiratory and digestive tract
-Anus, cervix, head and neck, and vagina
